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From: mnykanen@cc.helsinki.fi
Newsgroups: comp.sys.mac.programmer
Subject: Re: Breaking out of a series of routines
Message-ID: <2745.2699a0d0@cc.helsinki.fi>
Date: 10 Jul 90 09:33:04 GMT
References: <25526@cs.yale.edu> <5252@plains.UUCP>
Organization: University of Helsinki
Lines: 28

In article <5252@plains.UUCP>, puklich@plains.UUCP (Blayne Puklich) writes:
> tarr-michael@CS.Yale.EDU (michael tarr) wrote in article Breaking out of a
> 	series of routines:
>>On an error condition I wish to immediately stop processing a large file
>>and break out of about 10 routines that have been calling each other and
>>return to my main event loop. Is there any way to do this without
>>passing and error flag to each of the calling routines?
.stuff on C's set/longjmp() deleted..
> If you're using Pascal, probably a good way to do this is to pass a return
> code back up through each function (make them functions).  Then each and
> every call to the functions would be a test for a return code.  This really
> isn't as painful as it may seem like.  Pascal function return values are
> generally placed in a register (D0 if I remember right), so a test wouldn't
> be too time-consuming.

In Pascal a GOTO (yuck!) should suffice, at least as defined in the
standard. Since a Pascal GOTO is *not* just a branch instruction (it
even manages the run-time stack frames!) many microcomputer compilers do
not conform, though. But I too recommend functions returning error codes
on aesthetic grounds: they would make error recovery a part of normal
program behaviour, not 'an act of god' miraculously affecting the
control flow.
-- 
Matti Nyk{nen
CS Student at Helsinki U, Finland
email: mnykanen@cc.helsinki.FI

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